When creating your own Classes/Structs/Assets/ect, you'll sometimes want custom editors that pair with them. For example, a Gradient Editor so you can visually see what the Gradient looks like instead of editing the Gradient as if it were a Struct with a list of Colours.

Creating a Custom ControlWidget

The above are examples of ControlWidgets. The Inspector will try to find the appropriate one for each type, falling back on a Class/Struct editor (or none if it's not applicable). We can define our own with [CustomEditor]

public class MyClass
{
    public Color Color { get; set; }
    public string Name { get; set; }
}

[CustomEditor(typeof(MyClass))]
public class MyCustomControlWidget : ControlObjectWidget
{
    // Whether or not this control supports multi-editing (if you have multiple GameObjects selected)
    public override bool SupportsMultiEdit => false;

    public MyCustomControlWidget(SerializedProperty property) : base(property)
    {
        Layout = Layout.Row();
        Layout.Spacing = 2;

        // Get the Color and Name properties from the serialized object
        SerializedObject.TryGetProperty(nameof(MyClass.Color), out var color);
        SerializedObject.TryGetProperty(nameof(MyClass.Name), out var name);

        // Add some Controls to the Layout, both referencing their serialized properties
        Layout.Add( Create(color) );
        Layout.Add( Create(name) );
    }

    protected override void OnPaint()
    {
        // Overriding and doing nothing here will prevent the default background from being painted
    }
}

You can also check for certain attributes, so you can have a custom Password string editor that only appears when you've added the [Password] attribute

[CustomEditor(typeof(string), WithAllAttributes = new[] { typeof(PasswordAttribute) })]

Creating a Custom InspectorWidget

While creating Custom ControlWidgets is very powerful, sometimes you might want to replace the entire Inspector. This is especially useful for Editor Tools or Assets, and is done with the [Inspector] attribute.

using static Editor.Inspectors.AssetInspector;

// [CanEdit] is used for editing Assets with a certain file extension, if the thing you wish to
// inspect is NOT an Asset, you can use [Inspector(typeof(MyClass))]
[CanEdit("asset:char")]
public class CharacterInspector : Widget, IAssetInspector
{
    CharacterResource Character;
    ControlSheet MainSheet;

    // If this isn't an Asset Inspector, use CharacterInspector(SerializedObject so) : base(so)
    public CharacterInspector( Widget parent ) : base( parent )
    {
        Layout = Layout.Column();
        Layout.Margin = 4;
        Layout.Spacing = 4;

        // Create a header
        var header = Layout.Add( new Label( "My Inspector!", this ) );
        header.SetStyles( "font-size: 42px; font-weight: 600; font-family: Poppins" );

        // Create a ontrolSheet that will display all our Properties
		MainSheet = new ControlSheet();
		Layout.Add( MainSheet );
  
        // Add a randomize button below the ControlSheet
        var button = Layout.Add( new Button( "Randomize", "casino", this ) );
        button.Clicked += () =>
        {
        	foreach ( var prop in Test.GetSerialized() )
        	{
        		// Randomize all the float values from 0-100
        		if ( prop.PropertyType != typeof( float ) ) continue;
        		prop.SetValue( Random.Shared.Float( 0, 100 ) );
        	}
        };
        
        // Fill the remaining space and align everything else to the top
        Layout.AddStretchCell();
        
        // Populate the ControlSheet
        RebuildSheet();
    }

    // Rebuild the ControlSheet every hotload, so we catch any changes to the Asset
    [EditorEvent.Hotload]
    void RebuildSheet()
    {
        if ( Character is null ) return;
        if ( MainSheet is null ) return;
        MainSheet.Clear( true );
        
        // Populate the ControlSheet using only `float` Properties
        var so = Character.GetSerialized();
        so.OnPropertyChanged += x =>
        {
          Character.StateHasChanged(); // Mark as dirty so we can save
        };
        MainSheet.AddObject( so, x => x.PropertyType == typeof( float ) );   
    }


    // Only needed if Asset Inspector, and you are implementing IAssetInspector
    public void SetAssetPreview( AssetPreview preview )
    {
        // You can store the AssetPreview if you wish to interact with it later
        // Useful for an animation list that will update the Preview
    }

    // Only needed if Asset Inspector, and you are implementing IAssetInspector
    public void SetAsset( Asset asset )
    {
        Character = asset.LoadResource<CharacterResource>();
        RebuildSheet();
    }
}